[Spice-devel] [spice-gtk][PATCHv2] spice-widget: Protect against a NULL window

[Fabiano Fidêncio]

Return early instead of call gtk_widget_get_window() with a NULL window,
avoiding segfaults when running on windows using GTK3.

Program received signal SIGSEGV, Segmentation fault.
_gdk_windows_has_impl <window=window at entry=0x0> at gdkwindow.c:584
<gdb> bt
 #0  _gdk_window_has_impl (window=window at entry=0x0) at gdkwindow.c:584
 #1  0x70f02821 in gdk_win32_window_get_handle (window=0x0) at
     gdkwindow-win32.c:3459
 #2  0x00c759ef in update_display (display=0x1b18440) at
     spice-widget.c:1297
 #3  0x00c77280 in focus_in_event (widget=0x1b18440, focus=0x1b02b68) at
     spice-widget.c:1462
 #4  0x665727f5 in ?? () from C:\Program Files\VirtViewer
     (GTK3)\bin\libgtk-3-0.dll
 #5  0x00000000 in ?? ()
---
Changes since v1:
- Improve the commit message/shortlog
- Use g_return_if_fail instead of g_warn_if_fail in update_display()
---
 gtk/spice-widget.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/gtk/spice-widget.c b/gtk/spice-widget.c
index ae11073..23aca93 100644
--- a/gtk/spice-widget.c
+++ b/gtk/spice-widget.c
@@ -701,9 +701,12 @@ SpiceGrabSequence *spice_display_get_grab_keys(SpiceDisplay *display)
 static void try_keyboard_grab(SpiceDisplay *display)
 {
     GtkWidget *widget = GTK_WIDGET(display);
+    GdkWindow *window = gtk_widget_get_window(widget);
     SpiceDisplayPrivate *d = display->priv;
     GdkGrabStatus status;
 
+    g_return_if_fail(window != NULL);
+
     if (g_getenv("SPICE_NOGRAB"))
         return;
     if (d->disable_inputs)
@@ -731,8 +734,8 @@ static void try_keyboard_grab(SpiceDisplay *display)
                                             GetModuleHandle(NULL), 0);
     g_warn_if_fail(d->keyboard_hook != NULL);
 #endif
-    status = gdk_keyboard_grab(gtk_widget_get_window(widget), FALSE,
-                               GDK_CURRENT_TIME);
+
+    status = gdk_keyboard_grab(window, FALSE, GDK_CURRENT_TIME);
     if (status != GDK_GRAB_SUCCESS) {
         g_warning("keyboard grab failed %d", status);
         d->keyboard_grab_active = false;
@@ -1294,7 +1297,17 @@ static gboolean check_for_grab_key(SpiceDisplay *display, int type, int keyval)
 static void update_display(SpiceDisplay *display)
 {
 #ifdef G_OS_WIN32
-    win32_window = display ? GDK_WINDOW_HWND(gtk_widget_get_window(GTK_WIDGET(display))) : NULL;
+    GdkWindow *window;
+
+    win32_window = NULL;
+
+    if (display == NULL)
+        return;
+
+    window = gtk_widget_get_window(GTK_WIDGET(display));
+    g_return_if_fail (window != NULL);
+
+    win32_window = GDK_WINDOW_HWND(window);
 #endif
 }
 
-- 
2.1.0